Attitude gyro



Aplrifl 3, 1951 o. E. ESVAL ET AL 5 9 ATTITUDE GYRO Original Filed June4, 1942 2 Sheets-Sheet l FfiGi 0RD E.E$VAL INVENTORStWALTER WRIGLEY KENApril 9 1951 o. E. EsvAL ET AL 2,546,989

ATTITUDE GYRO Original Filed June 4, 1942 2 Sheets-Sheet 2 lllllllORLAND E. ESVAL. INVENTORS WALTER WREGLEY ATT RNEY Patented Apr. 3, 1951ATTITUDE GYRO Orland E. Esval, Huntington, Walter Wrigley,

East Hempstead, and Robert Haskins, Jr., Garden City, N. Y., assignorsto The Sperry Corporation, a corporation of Delaware Continuation ofapplication Serial No. 445,760, June 4, 1942. This application December21, 1945, Serial No. 636,384

1 Claim.

This invention relates to a gyroscopically controlled indicator foraircraft. The invention more particularly relates to a gyro verticalinstrument of a type that provides an indication at all times of the,position of the aircraft about its fore and aft axis and its athwartshipaxis. The instrument provides the pilot with an indication of theattitude of the aircraft through 360 of an inside or outside loop and ina 360 roll. The gyro indicating instrument of the present invention isuseful for stunt flying and every conceivable combat maneuver includingloops, barrel rolls and combinations thereof. No caging or locking meansis required in the improved instrument.

It is an object of the invention to construct a gyro vertical foraircraft in which the pilot obtains an indication of the position of thecraft about both its pitch and roll axes at all times.

This application is a continuation of application Serial No. 445,760,filed June 4, 1942, now Patent No. 1,859,208 for Attitude Gyros.

.Other objects of the invention will be more apparent from the followingdescription taken in connection with the accompanying drawings in whicha preferred form of the invention is shown.

Fig. 1 is a section through the casing of the gyroscopic indicator orgyro-vertical showing a plan view of the interior parts thereof.

Fig. 2 is a side elevation partly in section of the gyro verticalwithout the enclosing casing.

Fig. 3 is a front view of the Window of the indicating instrument asseen by the pilot in the position taken by the parts when the aircraftis in level flight.

Fig. 4 is a front view of the window of the indicating instrument in theposition taken by the parts when the aircraft is making a right bankedclimbing turn.

Fig. 5 is a development in reduced size of the indicator proper.

Fig. 6 is a diagram showing the path of an aircraft in making a loopshowing the four principal positions thereof.

Fig. '7 is a side elevation of the gyro vertical in the position i ofFig. 6 or when level.

Fig. 8 is a side elevation of the instrument in position 8 of Fig. 6,that is, when making a vertical climb.

Fig. 9 is a side elevation of the gyro vertical in position 9 of Fig. 6,that is, when the aircraft is upside down.

Fig. 10 shows the position of the device in position ll! of Fig. 6,which is a vertical dive.

Figs. 11 through 14 are plan views of the po- 5' sitions with referenceto the aircraft of the instrument corresponding to the positions shownin Figs. 7 through 10.

Figs. 15 through 18 illustrate what the pilot sees through the window ofthe device for each of the positions shown in Figs. 7 through 10.

The gyroscopic attitude indicator of the present invention is providedwith a suitable enclosure and support for the working parts of theinstrument. The operating parts are, therefore, housed in a casing 26which ha an opening 2! in the end thereof covered by a transparentmember 22 in the form of a window through which the gyroscopic indicatorcan be viewed. A frame 23 shown as of U-shaped form supports theinstrument and secures the same to the casing 20 in any suitablefashion, the frame being shown as bolted to the back of the face plate29' of the casing 20.

The frame 23 carries bearing means, which provides for the mounting of agimbal ring 21, in the form of a single elongated sleeve having spacedbearings 26 and 26', Fig. l. The gimbal ring 2! is U-shaped and at thecenter of the bend in the U, the ring carries a bearing shaft 28 whichis journaled in the bearings 26 and 26 and provides the mounting for themajor axis of the gyro instrument. Each arm of the U- shaped gimbal rin27 carries a bearing 36 which receives the trunnions 35 supporting therotor bearing frame 32 within which the rotor 50, Fig. 2, is journaledfor spinning about a substantially vertical axis in bearings 60, 6|. Thespherical shell or cover 32 is secured to the trunnions 3i and is freeto rotate in the bearings 30 which form the minor or athwartship axi forthe gyro instrument. The major axis for the instrument is situated inthe casing 28 so that it is substantially parallel to the fore and. aftaxis of the aircraft. Preferably the instrument is so mounted in itsouter casing that its minor horizontal axis is parallel to the frontwindow 22 and the major horizontal axis perpendicular thereto.

The gyro rotor is supported or mounted within the rotor bearing frame 32so that its axis is vertical, that is in line with the intersection ofthe meridian line 33 and the line on opposite sides of the indicatingface of the shell. The gyro rotor may :be driven by any suitable meansalthough electrical connections are shown for a three phase electricmotor driven rotor to accomplish this purpose.

The cover or shell 32 of the rotor bearing frame 32 is constructed tocontain 360 of attitude indications thereupon. The shell or cover 32paraxis of the instrument and the indications situated on thecircumferential surface thereof. Any form of shell having circularsymmetry about the athwartship axis of the instrument may obviously beemployed in this connection. The center of the surface of the,illustratively employed, spherical indicating cover 32 carries themeridian line 33 and cross-wise thereof are spaced indications whichshow the angular position or attitude of the aircraft with respect tothe vertical spin axis of the gyro rotor 5E The indicia upon theperipheral surface of the indicating cover 32, as shown in Fig. 5,includes a number of parallel arcs having numerical representations thatbegin at and continue to 90 around the circumference in both directions,i. e., upwardly and downwardly from the horizon reference line. Theindicia then decrease from 90 to 0 in both directions and with thenumerals inverted. The purpose of this arrangement is to permit normalreading in the event that the gimbal ring should be turned aroundthrough 180 when in gimbal lock position in which event the reverse sideof the indicator is brought before the window 22 as will hereinafter bemore particularly described. With the representations as shown it isimmaterial which side of the spherical indicator is before the window.The lower and upper hemispheres provided by the cover 32 are differentlycolored so that the pilot Will know when he is in upright or invertedposition and when he is climbing or diving.

The frame 23 or casing 20 carries a stationary index ring 36 in thefront of the same adjacent the window 22. The ring 36 has a rollreference in the form of a scale therein readable with the meridian lineto indicate to the pilot the degree of roll (bank) of the craft. Asshown, the ring indicator 36 carries an arcuate reference mark orstationary index 3'! such as a wire across the horizontal center of thesame. The fixed pitch index 3? is formed of two different colors, one ofwhich contrasts with one of the colors of the spherical cover 32 and theother of which contrasts with the other of the colors of the sphericalcover 32. This enables the pilot to obtain a correct indication of theattitude of the craft throughout 360 degrees of movement about its pitchaxis. The curve of the bar or wire permits the same to be positionedadjacent the indicating r surface of the spherical case 32. The innerdiameter of the ring is made substantially less than the major diameterof the sphere, and it is also preferably slightly less than the minordiameter 3| of the sphere, thus providing a reduced window or maskthrough which only th central portion of the face of the sphere isvisible and the fact that the sphere is truncated is not evident to theobserver.

For leading current into the rotor spinning motor, three electriccontact rings 4i are carried upon the end of the shaft 28 and each areengaged by a brush connected with a lead in wire 32. A wire 53 from oneof the rings ii leads to a flexible contact .5 which establishes anelectrical connection with the pointed end of a conductor 55 which inturn connects with the drivmotcr for therotor by means of a suitablelead (not shown)- A like flexible contact 46 establishes connection withthe pointed end of a further conductor 4'! for-the gyro motor whichcontact is electrically connected by a wire 48 to another one of therings ll. The third connection for the gyro motor is provided by a brushcontact 49 which electrically contacts with a conducting sleeve 5 .3insulated from the conductor 47 which contact is connected by wire 5|with the third of the lead in rings ii. The various contacts andconnections described receive current by way of leads 42 from a source(not shown) of three phase current in the present instance.

In operation, with the rotor axis in vertical position, and the aircraftflying level, the indication will be as shown in Fig. 3 with the pitchreference 3'! exactly upon one of the 0 or horizon lines on the surfaceof the cylindrical indicating shell 32 and the meridian line 33 exactlyvertical and in line with the indicia El and I8 on the roll referencescale. If the pilot makes a banked turn to the right the indicating faceof the shell 32 maintains its vertical position but casing 20 banks withthe plane. The pilot similarly is fixed or stationary relative to thecasing and ring 36 and therefore, so far as he is concerned, there isapparently no movement of the ring 36 and the horizon reference line 54would be inclined but it would intercept the center of the pitchreference bar 3?. Since the horizon line 54, however, as shown in Fig. 4is above the reference bar 31, the indication shown is a right handbanked turn with the craft climbing.

Relative positions of the casing 29 and generally spherical shell 32during a loop are shown in corresponding views l-l ll5, 8l2l6, 9i3l andlii--I4l 8. With the aircraft flying horizontally and level, the partsassume the relative positions shown in th first of the noted groups ofviews. As shown in Fig. 15, horizon reference line 54 is coincident withthe stationary pitch reference 31. The scale including portion of thecase 32 is subdivided into two segments of 180, each of which areprovided with different color backgrounds. The top scale as noted inFig. 5 is provided with a white background and the bottom scale iscontrasted therewith by having a black background. In turn, each of thenoted segments is composed of two quadrants having separate scaledindications thereon ranging between 0 and which are arranged in reversedrelation. A second horizon reference line is contained on the scale andis indicated at the 0 reference position in Fig. 5 by the referencenumber 55.

As the craft circles upwardly, it comes to a position 8, in Fig. 6, atwhich its nose is pointing in a vertical direction. The parts of theinstrument then assume the relative positions shown in Figs. 8, 12 and16. The observer then sees the attitude reference indication ili9li tothe rear of the pitch reference 37. In this position, the spin axis ofthe gyro rotor is momentarily aligned with the ax s of the gimbal ringwhich is a condition known as gimbal lock. When so situated the rotordoes not have its usual biaxial support so that any movement of thecraft about a horizontal axis perpendicular to the plane then determinedby the axes of the gimbal ring will cause the ring to rotate about itsaxis. This gimbal rotation is necessary in order to maintain theposition in space of the spin axis of the rotor and the tendency of thering to move in this manner becomes very pronounced when the gimbal lockcondition is approached. It is to be understood that this gimbalrotation takes place rapidly as the vertical position is passed through.With the present instrument, it has been practically determined that theposition of the gimbal ring is indeterminate when the gyro rotor is ingimbal lock position and following this position the relative parts arearranged in 180 ambiguity. The indeterminate character of the gimbalring position at this time is due to the fact that the loop maneuver maybe so well executed that no rotation of the gimbal ring is necessary tomaintain the direction of the spin axis of the rotor. On the other hand,a ring movement of 180 or 360 may be necessary. Because of the 180ambiguity of the changed gimbal rin position with respect to the gyrorotor, the position of the gyro rotor bearing case rather than the ringis employed in obtaining attitude indications in the present instrument-The reversed relation of the numerical degree representationson thescale will consequentl now be understood. As seen in Fig. 16, theindication obtained from the scale will remain constant regardless ofthe number of times that the ring rotates since the gyro rotor axisremains vertical. As the craft continues its movement through the loop,the numerical representations of the pitch scale appear upside down withreference to the reference 3'! indicating the fact that the craft isthen flying upside down.

At the top of the loop or in position 9, as shown in Fig. 6, theaircraft, casing 20 and observer are upside down with relation to theearth, and the shell or cover 32 and indications thereon maintain thesame constancy of position noted in the other views. In this invertedposition of the craft, the observer sees the second horizon ref erenceline 55 with the dark portion of the scaled rotor bearing caseuppermost. The numerical representations also continue to appearinverted.

In the position ll] of the loop, as indicated in Fig. 6, the craft isheadin downwardly or diving vertically towards the earth. This positioncorresponds to the reverse of position 8. The relative locations of thegyroscopic instrument parts are shown in Figs. 10, 14 and 18. This isalso a. location of gimbal lock. The observer sees only the whiteportion of the reference scale and regardless of gimbal lock rotation ofthe gimbal ring, the numerical representations will appear upright assoon as the craft resumes upright flight. It is evident that the pilotor observer of the instrument sees an attitude indication of the craftin any condition of flight.

In the design of the present instrument, it is necessary to employ agimbal ring and bearing case of low moment of inertia inasmuch asdeviation of the spin axis of the rotor from a vertical positionfollowing a gimbal lock condition is proportional to the same.

As schematically shown in Figs. 1 and 2, a control device of thecharacter specifically shown and described in the abandoned applicationof Orland E. Esval and John R. Muma for Tilt Correcting Devices, filedJanuary 24, 1942, Serial No. 428,140, may be employed to maintain thespin axis of the gyro rotor in an erected position during normalconditions of flight. In this instance, energy may be supplied theselective switch controlled solenoids in the erecting device by way ofleads 60, slip rings 6|, two separate lead wires be manually orautomatically effected in any of the customary manners of control notknown in the art.

As many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

An aeronautic attitude indicator having scalar marking halves withdistinctive backgrounds, each half consisting of two quadrants havingseparate numerals thereon reading from zero to and 90 to zero, and ameridian line dividing said scale, half the marking being on one side ofsaid line and half on the other, the ones on one side being upside downwith respect to those on the other side.

ORLAND E. ESVAL. WALTER WRIGLEY. ROBERT HASKINS, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,726,643 Borresen Sept. 3, 19292,036,229 Moss Apr. 7, 1936 FOREIGN PATENTS Number Country Date 140,482Great Britain Apr. 1, 1920 361,330 Germany Oct. 13, 1922 490,127 GermanyJan. 24, 1930

